In mobile communication systems, network operators are always concerned about radio resource usage. There is a general aim to optimise radio resource usage.
The provision of location services in mobile communication services, which is likely to be a key service aspect of future mobile communication systems, adds an additional burden to radio resources, since with current techniques there is a need for additional radio signals to provide information relating to a current location of a mobile station. In particular, in current proposals for location services there is a requirement for mobile stations which are in idle mode to be paged in order to obtain there location responsive to a paging request.
In customised applications for mobile network enhanced logic (CAMEL) phase 1 and phase 2, if a mobile station is active then the active session is used to identify a current cell global identity (CGI) or service area identity (SAI) for the mobile station. Additionally in CAMEL phase 2 if the mobile station is idle, then the last known location for the mobile station is returned. However, the last known location for the mobile station in idle mode may no longer provide useful information if the mobile station has moved significantly since its last known location was recorded.
In CAMEL phase 3, if a mobile station is active then the active session is again used to identify a current location of the mobile station, either the cell global identity (CGI) of GSM radio access network or service area identity (SAI) of UMTS radio access network. If the mobile station is idle, however, then the idle mobile station may be paged in order to obtain updated location information. The mobile station is paged if the current location is requested. This provides more useful location information in idle mode, but increases the radio resource usage.
In third generation based location services, as with CAMEL phase 3, if a mobile station is idle it is always paged and a location request issued to it again increasing the radio resource usage. Standard LCS functionality differs from CAMEL phase 3 in that paging is always done for an idle mode mobile station.
It is an aim of embodiments of the present invention to facilitate location services whilst minimising any usage of radio resources, and thereby minimise one or all of the problems mentioned above.